Expression of bone morphogenetic protein 7 in murine epididymis is developmentally regulated

Bone morphogenetic proteins (BMPs) have been shown to play a role in the fu nctional maintenance of the adult epididymis. To begin to investigate the r ole of BMP signal transduction during postnatal epididymal development, we examined the expression profile of Bmp7 in murine epididymis by in situ hyb ridization. Our data show that during early postnatal development (younger than 3 wk of age), Bmp7 transcripts are detected uniformly in epithelial ce lls throughout the epididymis. As the mice aged (from 3 to 4 wk), Bmp7 expr ession was gradually restricted to the initial segment, with increased leve ls. Bmp7 expression in the rest of the caput and corpus regions became unde tectable after 4 wk of age. However, after 4 wk of age, an ascending gradie nt of Bmp7 expression was observed in the epididymal epithelial cells in th e transition from the cauda epididymal tubule to the vas deferens. Such a u nique expression profile of Bmp7 strongly suggests that epididymis-produced BMP7 may play a role in the development and functional maintenance of the epididymis, and that Bmp7 expression in the epididymis is developmentally r egulated.